1. Field of the Invention
The present invention relates to colored and neutral dichroic light polarizers (DLPs) based on organic dyestuffs and to processes of preparation thereof. In one embodiment, the dichroic light polarizers are adapted for demanding operation or production conditions, such as for fabrication of laminated automobile windshields, for illumination devices, and for construction and architectural purposes. In addition, the invention relates to a method for preparing a film with high polarizing efficiency at high velocity of application.
2. Description of the Related Art
Dichroic light polarizers (DLPs) can be based on the organic dyes having sulfoacids of azo or polycyclic compounds or mixtures thereof. These dyes are capable of forming lyotropic liquid crystal phases that form stable lyotropic liquid crystals and liquid crystal compositions. (See for example PCT/US94/05493, published Aug. 8, 1994.)
In addition to the dyes, these liquid crystal materials may contain certain water-soluble, low molecular organic compounds, antioxidants, inhibitors, and/or surfactants. A thin molecularly ordered dye film is formed during the deposition of the lyotropic liquid crystal materials onto a substrate surface with simultaneous mechanical orientation, and subsequent removal of solvent. This film is a polarizing coating that is capable of converting natural unpolarized light into polarized light.
The dichroic light polarizers obtained using such liquid crystal materials offer high thermal and radiation stability, and exhibit good polarization characteristics. Such dichroic light polarizers based on polarizing coatings have the following disadvantages. 1) These dichroic light polarizers have insufficient polarizing efficiency due to light scattering at the interfaces formed by the domain structure of the polarizing coating. 2) These dichroic light polarizers are based on a polarizing coating having polarization vector which is ordered only along the direction of macroscopic orientation. 3) Current preparation methods cannot provide polarizing coatings with preset distribution of the color and the orientation of polarization vector.